How to improve traffic for an affiliate site

I have a site for promoting affiliate products about web hosting, coupons and forum themes. But its traffic is very low and doesn't have traffic from search engines. How to improve it.
I used content from source sites , is that reason for low traffic from search engines, because it was duplicated content?

When people ask this question I always ask them the following questions:

When you came up with the idea for this website, what was your primary focus on? Were you thinking about how can I make money with a website? or Were you thinking what type of website would be in demand? or Were you thinking something else?

If you are like most people, then you were probably thinking "What type of website can I make money with?" The problem with focusing on that is that you end up picking a website business model that there isn't any demand for.

If you want people to willingly come visit your website, then there has to be a reason "that is in their self interest" for them to want to visit your website. If there isn't a legitimate reason why a person would want to visit your website before buying one of your affiliate products, then you will find it really, really hard to get people to visit the site at all. You will have to trick them into visiting somehow. And if you manage to trick them into visiting, they still won't convert for you anyway.

Do you understand what I mean?

You will make money with a website a lot easier if you start out by figuring out "What type of website can I create that people will want to come to?" "What can I offer people that they really want or need?"

Once you have come up with a good idea for that, then you ask yourself "How can I make money with that type of website?" What would I have to do in order to be able to monetize that traffic? Is it going to be worth my time doing that project or can I come up with a better idea that more people would want that would be more easily monetized?

Okay cool.

If you want to attract people who are searching in the search engines for the keywords "godaddy coupons" then you should build a page on your website that is all about Godaddy coupons. You have to have plenty of unique content on the page if you want it to rank well. So that means you would probably add some text to the page that talks about Godaddy coupons. Come up with things that make your site sound better like "The coupons we list here on our website are tested daily for efficacy to make sure that when you go to actually use the coupons they are going to work. These coupons have been updated for July 2015." Write about things like that. The more text you add to the page the better.

Follow excellent on-page SEO protocols when creating that page. Just do the best that you can do.

Then create a page like that for your hosting coupons. And do the same things.

Then create a page like that for your forum theme coupons. And do the same things for that.

Then you are going to have to juice up the pages on the site somehow. You can do that by getting links from other websites pointing back to your website. You can also do that by adding more pages to your site about whatever you want and then linking from those new pages back to the other coupon pages you want to rank really high.

Keep tweaking your on-page metrics over time. Keep looking for ways to get a better link to your website.

That is how it works in a nutshell.

Most of the coupon sites I have seen in my travels were entirely dedicated to one type of coupon or one type of company. For example, you could have an entire site that just promotes web hosting coupons. You could have an entire site that promotes Wordpress themes, etc.

If you build an entire site to focus on one narrow topic like that it tends to give you a ranking advantage over the other guys. You can pick a more keyword focused domain name. All of your content is much more focused and silo'd. Those things matter.

Hope that helps.